1. Field of the Invention
The invention relates to a seal for a starer bar head to be used in a continuous caster, in particular in a continuous caster for casting steel strands having strip cross section or billet or bloom cross section, wherein the seal extends into a gap provided between the starer bar head and the side walls of a continuous casting mold under direct contact of the side faces of the starer bar head and of the mold side walls, as well as to various methods of obtaining tightness between a starter bar head and a continuous casting mold.
2. Description of the Related Art
At the beginning of continuous casting it is necessary to provide tightness between a so-called starter bar head, on which the cast strand is cast and by aid of which it is withdrawn from the mold, and the cavity of the mold, into which the metal melt is poured, in order to reliably prevent the penetration of metal melt. To this end, it is known to seal the starer bar head relative to the mold walls by means of sealing ropes, such as asbestos ropes. In former times, the attachment of such seals was effected from above, which was disadvantageous insofar as the accessiblity from above is limited, in particular with continuous casting molds having narrow cross sections, such as, for instance, for casting thin slabs and strands having strip cross section or billet or bloom cross section.
From AT-B-352,924 it is known to provide a starter bar head with a seal that is installable prior to introducing the starter bar head into the continuous casting mold and is usable several times, wherein the starer bar head has an encircling recess in which the seal is inserted. The seal is designed as a fiat seal, being supported by a spring leaf annularly extending on its rear.
From DE-A-28 11 157 seals of the initially described type are known, which are inserted in an encircling peripheral recess of the starter bar head, wherein, according to one embodiment, an elastic seal is designed like a hose and may be blown up by a gaseous medium. The seals known from that document likewise are attachable to the starter bar head prior to its introduction and are re-usable several times. However, difficulties may arise when introducing the starter bar head into the mold insofar as the seal located in the peripheral recess is completely cut off from visual inspection after the starter bar head has been introduced into the mold such that possible damage to the seal occurring during the procedure of introducing the starter bar head into the continuous casting mold cannot be recognized.
From EP-A-0 114 309 it is known to provide a starter bar head with a seal prior to its introduction into the mold, wherein a seal holder to be destroyed by the casting metal is put on the starter bar head and the seal is arranged between the starter bar head and the seal holder. According to a first embodiment, a peripherally extending encircling groove is formed between the seal holder and the starter bar head, in which the seal is inserted. With this embodiment, inspection of the seal after introduction of the starter bar head into the continuous casting mold is no longer possible.
According to another embodiment of EP-A-0 114 309, the seal is formed by a mat covered by a plate-shaped seal holder. Although this provides for a good protection to the seal during the procedure of introducing the starter bar head into the continuous casting mold, this variant--like that described above--is expensive, because, in addition to the seal, a separate seal holder must be produced and installed, which can be used only once, since it is destroyed by the casting metal flowing in.